ACPI / PM: Expose current status of ACPI power resources

Since ACPI power resources are going to be used more extensively on new hardware platforms, it becomes necessary for user space (powertop in particular) to observe some properties of those resources for diagnostics purposes. For this reason, expose the current status of each ACPI power resource to user space via sysfs by adding a new resource_in_use attribute to the sysfs directory representing the given power resource. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ACPI / PM: Expose current status of ACPI power resources
Since ACPI power resources are going to be used more extensively on new hardware platforms, it becomes necessary for user space (powertop in particular) to observe some properties of those resources for diagnostics purposes. For this reason, expose the current status of each ACPI power resource to user space via sysfs by adding a new resource_in_use attribute to the sysfs directory representing the given power resource. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Rafael J. Wysocki
1 parent 836aedb141
Showing 4 changed files with 41 additions and 1 deletions Side-by-side Diff
Documentation/ABI/testing/sysfs-devices-resource_in_use
drivers/acpi/power.c
drivers/acpi/scan.c
include/acpi/acpi_bus.h
+What:		/sys/devices/.../resource_in_use
+Date:		January 2013
+Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+Description:
+		The /sys/devices/.../resource_in_use attribute is only present
+		for device objects representing ACPI power resources.
+
+		If present, it contains a number (0 or 1) representing the
+		current status of the given power resource (0 means that the
+		resource is not in use and therefore it has been turned off).
+
+		This attribute is read-only.
@@ -87,6 +87,12 @@
                              Power Resource Management
    -------------------------------------------------------------------------- */
  
+static inline
+struct acpi_power_resource *to_power_resource(struct acpi_device *device)
+{
+	return container_of(device, struct acpi_power_resource, device);
+}
+
 static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
 {
 	struct acpi_device *device;
@@ -94,7 +100,7 @@
 	if (acpi_bus_get_device(handle, &device))
 		return NULL;
  
-	return container_of(device, struct acpi_power_resource, device);
+	return to_power_resource(device);
 }
  
 static int acpi_power_resources_list_add(acpi_handle handle,
@@ -678,6 +684,21 @@
 	kfree(resource);
 }
  
+static ssize_t acpi_power_in_use_show(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf) {
+	struct acpi_power_resource *resource;
+
+	resource = to_power_resource(to_acpi_device(dev));
+	return sprintf(buf, "%u\n", !!resource->ref_count);
+}
+static DEVICE_ATTR(resource_in_use, 0444, acpi_power_in_use_show, NULL);
+
+static void acpi_power_sysfs_remove(struct acpi_device *device)
+{
+	device_remove_file(&device->dev, &dev_attr_resource_in_use);
+}
+
 int acpi_add_power_resource(acpi_handle handle)
 {
 	struct acpi_power_resource *resource;
@@ -724,6 +745,9 @@
 	result = acpi_device_add(device, acpi_release_power_resource);
 	if (result)
 		goto err;
+
+	if (!device_create_file(&device->dev, &dev_attr_resource_in_use))
+		device->remove = acpi_power_sysfs_remove;
  
 	mutex_lock(&power_resource_list_lock);
 	list_add(&resource->list_node, &acpi_power_resource_list);
@@ -791,6 +791,9 @@
  
 	acpi_power_add_remove_device(device, false);
 	acpi_device_remove_files(device);
+	if (device->remove)
+		device->remove(device);
+
 	device_del(&device->dev);
 	/*
 	 * Drop the reference counts of all power resources the device depends
@@ -280,6 +280,7 @@
 	struct mutex physical_node_lock;
 	DECLARE_BITMAP(physical_node_id_bitmap, ACPI_MAX_PHYSICAL_NODE);
 	struct list_head power_dependent;
+	void (*remove)(struct acpi_device *);
 };
  
 static inline void *acpi_driver_data(struct acpi_device *d)
	1	+What: /sys/devices/.../resource_in_use
	2	+Date: January 2013
	3	+Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
	4	+Description:
	5	+ The /sys/devices/.../resource_in_use attribute is only present
	6	+ for device objects representing ACPI power resources.
	7	+
	8	+ If present, it contains a number (0 or 1) representing the
	9	+ current status of the given power resource (0 means that the
	10	+ resource is not in use and therefore it has been turned off).
	11	+
	12	+ This attribute is read-only.
...	...	@@ -87,6 +87,12 @@
87	87	Power Resource Management
88	88	-------------------------------------------------------------------------- */
89	89
	90	+static inline
	91	+struct acpi_power_resource to_power_resource(struct acpi_device device)
	92	+{
	93	+ return container_of(device, struct acpi_power_resource, device);
	94	+}
	95	+
90	96	static struct acpi_power_resource *acpi_power_get_context(acpi_handle handle)
91	97	{
92	98	struct acpi_device *device;
...	...	@@ -94,7 +100,7 @@
94	100	if (acpi_bus_get_device(handle, &device))
95	101	return NULL;
96	102
97		- return container_of(device, struct acpi_power_resource, device);
	103	+ return to_power_resource(device);
98	104	}
99	105
100	106	static int acpi_power_resources_list_add(acpi_handle handle,
...	...	@@ -678,6 +684,21 @@
678	684	kfree(resource);
679	685	}
680	686
	687	+static ssize_t acpi_power_in_use_show(struct device *dev,
	688	+ struct device_attribute *attr,
	689	+ char *buf) {
	690	+ struct acpi_power_resource *resource;
	691	+
	692	+ resource = to_power_resource(to_acpi_device(dev));
	693	+ return sprintf(buf, "%u\n", !!resource->ref_count);
	694	+}
	695	+static DEVICE_ATTR(resource_in_use, 0444, acpi_power_in_use_show, NULL);
	696	+
	697	+static void acpi_power_sysfs_remove(struct acpi_device *device)
	698	+{
	699	+ device_remove_file(&device->dev, &dev_attr_resource_in_use);
	700	+}
	701	+
681	702	int acpi_add_power_resource(acpi_handle handle)
682	703	{
683	704	struct acpi_power_resource *resource;
...	...	@@ -724,6 +745,9 @@
724	745	result = acpi_device_add(device, acpi_release_power_resource);
725	746	if (result)
726	747	goto err;
	748	+
	749	+ if (!device_create_file(&device->dev, &dev_attr_resource_in_use))
	750	+ device->remove = acpi_power_sysfs_remove;
727	751
728	752	mutex_lock(&power_resource_list_lock);
729	753	list_add(&resource->list_node, &acpi_power_resource_list);
...	...	@@ -791,6 +791,9 @@
791	791
792	792	acpi_power_add_remove_device(device, false);
793	793	acpi_device_remove_files(device);
	794	+ if (device->remove)
	795	+ device->remove(device);
	796	+
794	797	device_del(&device->dev);
795	798	/*
796	799	* Drop the reference counts of all power resources the device depends
...	...	@@ -280,6 +280,7 @@
280	280	struct mutex physical_node_lock;
281	281	DECLARE_BITMAP(physical_node_id_bitmap, ACPI_MAX_PHYSICAL_NODE);
282	282	struct list_head power_dependent;
	283	+ void (remove)(struct acpi_device );
283	284	};
284	285
285	286	static inline void acpi_driver_data(struct acpi_device d)